The forward motility protein (FMP) has potential for use as a contraceptive vaccine to control population growth. FMP has also the potential to rectify some of the problems of human infertility (due to low sperm motility): a great social curse in all human races. It has also the potential for solving some of the problems of animal breeding (due to inadequate sperm motility) thereby enhancing milk and meat production.
Population explosion is a major problem in all developing countries including India. Although several contraceptive methods are available, they have the undesirable side effects/lower efficacy. In addition some of these methods are rather expensive.
Another global social problem is human infertility. Approximately 15% of couples are believed to be infertile. One reason for human infertility is due to low sperm motility. Although several sophisticated Assisted Reproductive Technologies (e.g. IVF in vitro Fertilization, ICSI: Intracytoplasmic Sperm Injection) are available to solve the problems of oligospermic and asthenozoospermic patients (with low sperm motility), these technologies are highly expensive and the success rate is extremely low.
To solve the problems of population explosion and human infertility it is essential to have an in-depth understanding of the biochemical basis of the reproductive processes. The following section briefly reviews the literature on epididymal sperm maturation: an important event in the male reproductive function.
Mammalian testicular spermatozoa are immotile and infertile. During transit through epididymis these cells acquire forward motility which is essential for their ability to fertilize the female eggs. Biochemical basis of the epididymal sperm maturation process is not well understood. Reference may be made to Hoskins D. D., Brandt H. and Acott T. S., Fed Proc, 37, 2534-2542, 1978; Majumder G. C., Dey C. S., Halder S. and Barua M., Arch Androl, 24, 287-303, 1990. Epididymal plasma (EP)/seminal plasma (SP) possess a factor that induces forward motility (FM) in vitro in the caput epididymal immature sperm derived from bull. Reference may be made to Acott, T. S., and Hoskins, D. D. J Biol Chem, 253, 6744-6750, 1978, Hoskins, D. D., Brandt, H. and Acott, T. S. Fed. Proc. 37, 2534-2542, 1978. In the case of hamster reference may be made to Cornwall, G. A., Smyth, T. S., Vindivich, D., Harter, C., Robinson, J. and Chang, T. S. K. Biol Reprod 35, 1065-1074, 1986. And in case of goat reference may be made to Jaiswal, B. S. and Majumder, G. C., Int J Androl, 19, 97-102, 1996. Hoskins and his associates (Acott, T. S. and Hoskins, D. D. J Biol Chem, 253, 6744-6750, 1978, Hoskins, D. D., Brandt, H. and Acott, T. S. Fed. Proc. 37, 2534-2542, 1978) have partially purified the active principle from bovine SP and EP and it has been designated as forward motility protein (FMP). FMP originates from epididymis, after its synthesis in epididymis the factor is secreted into epididymal plasma and subsequently it passes to seminal plasma (Brandt, H., Acott, T. S., Johnson, D. J. and Hoskins, D. D. Biol. Reprod. 19, 830-835, 1978). For the isolation of FMP, these investigators have used several fractionation techniques as elaborated below. The bovine SP was heated at 90.degree. C. for 10 min. and then centrifuged at 1,78,000xg for 60 min to remove the precipitated proteins. The resulting supernatant fluid was subjected to Sepharose 6B chromatography using a buffer containing 4 M urea, 100 mM NaCl, 10 mM dithiothreitol and 100 mM Tris-HCl, pH 7.5. By these procedures FMP was purified to about 15-fold. Alternatively the factor was also partially purified further by concanavalin A-agarose affinity chromatography of the heat-treated SP. FMP binds to concanavalin A and was eluted with 0.25 M-.alpha.-methyl-D-mannoside. The isolated FMP contained several proteins as shown by sodium dodecyl sulphate (SDS)-gel electrophoresis and the extent of purity of FMP is not known. By using similar methods FMP was also isolated from bovine EP although the degree of its purification is not known. FMP is a 37 KDa heat-stable glycoprotein that is believed to be essential for the initiation of sperm FM during the epididymal sperm maturation. FMP induces forward motility in vitro in the bovine immature/immotile caput-epididymal spermtozoa.